川中地区上三叠统须家河组储层成岩相

Reservoir diagenetic facies of the Upper Triassic Xujiahe Formation in the central Sichuan Basin

利用铸体薄片、阴极发光、扫描电镜等资料,对川中地区上三叠统须家河组储层成岩作用类型及特征进行了综合研究,在此基础上划分成岩相类型,建立了不同类型成岩相测井曲线特征,进行了研究区须家河组成岩相纵向及平面分布研究。结果表明,研究区须家河组碎屑岩储层经历了机械压实、硅质胶结、碳酸盐胶结破坏性成岩作用及溶蚀、绿泥石胶结建设性成岩作用。将储层划分为低孔特低渗溶蚀相、特低孔超低渗压实-溶蚀相、致密强压实相、致密硅质胶结相、致密方解石胶结相5种成岩相类型。低孔特低渗溶蚀相及特低孔超低渗压实-溶蚀相主要分布在须二段、须四段与须六段下部,致密强压实相、致密硅质胶结相、致密方解石胶结相在纵向及横向上封隔有利成岩相,形成岩性圈闭。平面上将川中地区须家河组储集层划分为低孔特低渗溶蚀相、特低孔超低渗压实-溶蚀相及致密强压实相分布区。

Based on data of cast-slice,cathodeluminescence and SEM analyses data,the present paper comprehensively investigated types and characteristics of reservoir diagenesis of the Upper Triassic Xujiahe Formation in the central Sichuan Basin,distinguished types of diagenetic facies,discussed logging curve features of diagenetic facies,and examined vertical and lateral distributions of diagenetic facies.The results demonstrated that clastic reservoirs of the Xujiahe Formation in the studied area experienced destructive diagenesis by compaction,siliceous cementation,carbonate cementation and constructive diagenesis by denudation,chlorite cementation.The reservoirs could be divided into five types of diagenetic facies,including low porosity particularly low permeability corroded facies,particularly low porosity extremely low permeability compacted-corroded facies,intensively compacted tight facies,siliceous cemented tight facies and calcite cemented tight facies.Of which the two former facies occurred mainly in lower parts of the second,forth and sixth members of the Xujiahe Formation,while the rest three facies vertically and laterally isolated other favorable diagenetic facies,forming lithologic traps.Horizontally,reservoirs of the Xujiahe Formation of the central Sichuan Basin could be divided into three areas according to different diagenetic facies,such as low porosity particularly low permeability corroded facies,particularly low porosity extremely low permeability compacted-corroded facies and intensively compacted tight facies.